more conservative update of Haskell stack (amending 04e54f57a869): 13.0 still lacks notable packages like "Agda" or "darcs";
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: setup Glasgow Haskell Compiler via Stack
set -e
isabelle_stack setup
isabelle_stack ghc -- --version
echo -n "$(standard_path "$(isabelle_stack path --programs)")" > "$ISABELLE_STACK_ROOT/ISABELLE_GHC_PROGRAMS"